Specialized tools and equipment are used in the exploration and production of oil and gas. These tools and equipment are built to withstand ordinary wear and tear they will encounter in the extreme environments and applications in which they will be used. For example, hinged elevators repeatedly open and close around heavy weighted drill pipe to support the pipe segment while it is affixed to a drill pipe strand. The elevator is subjected to continuous wear forces caused by its hydraulic manipulation and by the extreme force placed upon the elevator when supporting drill pipe. Overtime the wear forces applied to the elevator would eventually lead to structural failure. Failure of the elevator could lead to suspended drill pipe being dropped on a rig floor. Costly equipment could be damaged. Rig workers could be injured.
The elevator is one example of a tool used on a rig. Many other tools and equipment are used. Each is critical to the operation. And its failure may lead to catastrophic property damage and personal injury. For these reasons, oil and gas tools and equipment are routinely inspected for wear. Take the elevator for example. After a predetermined time in operation on a drilling rig, the elevator is taken out of service and returned to the rental tool company. The company will have a trained inspector disassemble the elevator and visually inspect each component part. The inspector will determine which component parts contain sufficient wear that their replacement is necessary. The inspector may replace or have the part repaired. The tool is reassembled and ready for shipment back to a rig for further use.
The inspector is fallible. He may not inspect all component parts. He may confuse the tool with another and apply different inspection criteria to the tool that are not applicable. The inspection may be interrupted. When he resumes the inspection several hours or a day later, he may not remember where to begin. Component parts may be missed. Many times inspections are started by one inspector and completed by another. When this happens, there is propensity to overlook parts, thinking the other inspector was responsible for the part's inspection. Finally, the inspector may pass a tool that he did not fully inspect.
There is a need for an inspection method that overcomes the drawbacks associated with prior inspection techniques.